Electronic content, such as electronic media content, can be protected using digital rights management (DRM) techniques. DRM techniques can utilize various licenses to protect content and limit how and by whom the content can be consumed. So, for example, a user may purchase a piece of content over the Internet and a license associated with that content may limit how many times and on what devices the content can be consumed. Some DRM techniques allow a user to transfer or move a piece of content from one computing device to another. So, for example, a user may purchase a song over the web and store the song on their personal computer. They may later transfer that song to their laptop device or a hand-held device.
Some DRM techniques enable users to move content, through a “move” operation, from device to device, but attempt to limit the user from consuming the content on a device from which the content was transferred. The complexity of implementing a “move” operation arises from the fact that today, DRM state information is stored locally on a user's computing device. Thus, such DRM state information can be subject to what is known as a rollback attack. In a rollback attack, state variables associated with DRM state for a piece of content are copied to a location, such as an external hard drive or use an operating system feature such as a volume snapshot, and the content is then moved to another device. The state variables are then restored on the transferring device so that it looks to the DRM system as if no state changes have taken place when, in fact, the content and the associated license have been moved or copied to a different device.
Attacks such as this and others can thus allow the user to consume the transferred content on two devices in an unauthorized manner.